Newly-released police interrogation tapes and documents tied to a controversial rape allegation case reveal new details about what happened the night when Maryville, Mo., teen Daisy Coleman accused an older high school student of raping her.

Coleman accused Matthew Barnett, then a 17-year-old high school senior and the grandson of a former state representative, of raping her in 2012, and leaving the then-14-year-old drunk and incoherent freshman on her family's front lawn in freezing temperatures.

The Kansas City Star/AP Photo

Matthew Barnett walks into the courthouse with his legal counsel J.R. Hobbs for a hearing Jan. 9, 2014 in Maryville, Mo.

But just last month, prosecutors released the entire case file, which included interrogation tapes of Barnett talking with a Nodaway County Sheriff's Department investigator.

In the taped interview with police, taken just hours after the alleged assault, Barnett admits to having sex with Coleman but said the two willingly had sex at his house, and then Coleman started drinking in excess afterwards. He also says in the police interview that when he picked Coleman up from her house on the night of Jan. 8, 2012, she appeared "buzzed" but not drunk.

Nodaway County Sheriff Dept.

Photo of Matthew Barnett's family basement where the teens were drinking on the night of Jan. 8, 2012.

The case file also included July 2012 criminal depositions of Daisy Coleman and her mother, Melinda Coleman, with Nodaway County prosecutor Robert Rice. In Daisy's interview, she admitted to texting with Barnett about "once a month" before the alleged incident and that "sometimes me and my friends would see if he would bring us alcohol." She also indicated that it was possible that she said she would provide him with sexual favors if he brought her alcohol.

On the night of the alleged assault, text messages extracted from Daisy Coleman's phone show that she and Barnett exchanged texts about getting together to party.

By all accounts, Coleman drank at least five shots of vodka at Barnett's house. But the critical question is when she drank them because Missouri law states that a 14-year-old girl cannot consent to sex if she's incapacitated.

Throughout the investigation, Barnett did not dispute that he and Coleman had sex, but he insisted it was consensual and that Coleman was not drunk at the time. Another boy at the house told police that Coleman drank heavily after her encounter with Barnett.

On the other hand, Daisy Coleman had always maintained that she snuck out of her house with her then-13-year-old friend after consuming alcohol in her home and was picked up by Barnett. Coleman said then she blacked out after drinking too much and accused Barnett of raping her and dropping her off on her front yard.

The identities of alleged sex assault victims are generally not published, but Coleman's family decided to go public with her identity and accusations.

The case divided the community and the family said they were harassed. Coleman was suspended from the cheerleading team after admitting to drinking and said she was bullied at school. Things got so bad that the family said they were forced to move, but that didn't stop the slew of online attacks.

"The stuff on Facebook and Twitter was just unbelievable, so horrible ... saying stuff like, 'Why don't you slit your wrists,'" Melinda Coleman told "20/20" in a January interview.

The case caught national media attention in October 2013 when the Kansas City Star reported on the allegations and Robert Rice's decision to drop charges against Barnett, who was initially charged with felony sex and child endangerment.

The state at the time appointed a special prosecutor to re-investigate the case, which ended in Barnett pleading guilty to the misdemeanor charge on Jan. 9, 2014.

"Before, it was absolutely nothing. Everybody thought it was just one big giant lie," Charlie Coleman told "20/20" at the time. "But then, there's also an injustice in it not being able to be the way we wanted. I guess I'm a little disappointed but not discouraged."

Barnett and his attorney maintain that the fact that two independent investigations have cleared him proves that he didn't do anything wrong that night except for leaving Coleman outside in the cold.

Today, Coleman is back at school and told "20/20" she is happier and healthier than ever, but her mother vows she is not done fighting for justice.

"It's not in me to stop fighting," Melinda Coleman told "20/20." "So if ... I need to die from this, then I will, and I'm OK with that."